Section 1218ZBD | When costs are taken to be incurred
From legislation.gov.uk
(1)For the purposes of this Chapter, the costs that have been incurred on a production of an exhibition at a given time do not include any amount that has not been paid unless it is the subject of an unconditional obligation to pay.
(2)Where an obligation to pay an amount is linked to income being earned from the production of the exhibition, the obligation is not treated as having become unconditional unless an appropriate amount of income is or has been brought into account under section 1218ZBA.